linux-kernel - Re: [PATCH 3/3] pinctrl: exynos: ack level-triggered interrupts before unmasking

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Date:	Thu, 13 Jun 2013 18:40:24 +0200
From:	Tomasz Figa <tomasz.figa@...il.com>
To:	Doug Anderson <dianders@...omium.org>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Olof Johansson <olof@...om.net>,
	Simon Glass <sjg@...omium.org>,
	Luigi Semenzato <semenzato@...omium.org>,
	Ilho Lee <ilho215.lee@...sung.com>,
	김은기 <eunki_kim@...sung.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>
Subject: Re: [PATCH 3/3] pinctrl: exynos: ack level-triggered interrupts before unmasking

On Thursday 13 of June 2013 09:34:43 Doug Anderson wrote:
> Tomasz,
> 
> On Thu, Jun 13, 2013 at 3:54 AM, Tomasz Figa <tomasz.figa@...il.com> 
wrote:
> > Hi Doug,
> > 
> > On Wednesday 12 of June 2013 10:33:19 Doug Anderson wrote:
> >> A level-triggered interrupt should be acked after the interrupt line
> >> becomes inactive and before it is unmasked, or else another interrupt
> >> will be immediately triggered.  Acking before or after calling the
> >> handler is not enough.
> > 
> > Nice catch.
> > 
> > I guess that pinctrl-s3c64xx will need similar fix as well, won't it?
> 
> It needs this whole series of 3, probably.  The mask and unmask need
> the lock and as well as the acking for level interrupts.
> 
> I don't have any way to test that code but it's a pretty simple change
> to make.  Do you want to do it or do you have an idea of someone who
> should?

I'll take care of s3c64xx, probably as a part of my patches finally adding 
DT support for it, as without them the pinctrl-s3c64xx driver is just 
sitting there unused.

> > I think you can eliminate most of the code by doing this following 
way:
> >         if (irqd_get_trigger_type(irqd) & IRQ_TYPE_LEVEL_MASK)
> >         
> >                 exynos_gpio_irq_ack(irqd);
> 
> Duh, right.  OK, v2 coming shortly.

Good!

> Thank you for pointing out the
> right way to do this!  :)

You're welcome.

Best regards,
Tomasz

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